Eye tracking may be used in computing systems to detect user inputs made by gazing at virtual and/or real objects. For example, a computing device may be configured to detect user interactions with a displayed user interface by detecting a location on the user interface at which the user gazes, and registering an input at that location.
However, the use of eye tracking as a computing system input mechanism may pose various challenges. For example, some eye tracking systems may utilize images of a center of a user's pupil and also of corneal reflections from glint light sources to determine a line of sight of the user's eye. However, different users may have anatomical differences that can affect such a determination. For example, the location of the fovea on the retina may differ from person to person. As such, the visual axis of the eye (i.e. the axis extending from the physical object imaged on the user's fovea to the fovea) may be offset from the optical axis of the eye (i.e. the axis extending through the center of the pupil to the back pole of the eyeball). As the image data is used to determine an estimate of the optical axis of the eye, such an offset may complicate the accurate estimate of an actual location at which the user is gazing.